(a) Cross section of the 95 GHz TE011 cylindrical cavity model used in the electromagnetic simulations, (b) front view of the coupling insert with the metal sphere mounted. (c) Side view of the lower part of the insert with the metal sphere.
Basic scheme of the 95 GHz measuring setup. (1) Variable frequency mw source; (2) pulse former (PIN switch); (3) circulator; (4) coupling mechanism; (5) TE011 cavity; (6) quadrature mixer; (7) variable phase shifter.
(a) Recorded quadrature voltage profiles of −10 dBm 95 GHz mw pulse of 100 ns applied to the critically coupled TE011 cylindrical cavity with circular iris of 0.8 mm diameter. (b) Relative power profile. The flat part during the pulse (dotted line) yields the return loss of 37 dB (|Γ| = 1.4 × 10−2). The linear approximation of the power decay after the mw pulse switched is off (dashed line) yields the power decay time of 3.8 ± 0.1 ns (ringing time TR = 7.6 ± 0.2 ns) which corresponds to Q0 = 4500 ± 100.
Recorded x-channel voltage profiles of −10 dBm 95 GHz mw pulse of 100 ns applied to TE011 cylindrical cavity with circular iris of 0.8 mm for undercoupled (β < 1), critically coupled (β = 1) and overcoupled (β > 1) conditions.
Experimental (filled symbols) and calculated (unfilled symbols) coupling coefficient dependence on the position of the metal sphere of 0.78 mm (0.8 mm for calculation) diameter for a 95 GHz TE011 cavity. The zero-position corresponds to the sphere centered above the iris hole. (a) and (b) show the results for iris diameter of 0.8 mm and 0.85 mm, respectively.
Experimental (filled symbols) and calculated (unfilled symbols) frequency shift of the cavity resonance frequency depending on the position of the coupling sphere. (a) and (b) show the results for iris diameter of 0.8 mm and 0.85 mm, respectively.
Coupling parameter and unloaded quality factor Q0 of the W-band TE011 cavity with coupling sphere positioned above iris of 0.85 mm diameter which contains the cylindrical water sample of variable diameter, as obtained from electromagnetic calculations.
Coupling parameter (●) and ringing time (■) depending on the position of the coupling sphere for the Q-band (34 GHz) TE011 cavity.
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